Python - 面向对象编程 - 反射 hasattr、getattr、getattr、delattr

def hasattr(*args, **kwargs): 
    """
    Return whether the object has an attribute with the given name.
    This is done by calling getattr(obj, name) and catching AttributeError.

    """
    pass

def getattr(object, name, default=None): 
    """
    getattr(object, name[, default]) -> value
    Get a named attribute from an object; getattr(x, ‘y‘) is equivalent to x.y.
    When a default argument is given, it is returned when the attribute doesn‘t
    exist; without it, an exception is raised in that case.

    """
    pass

def setattr(x, y, v):
    """
    Sets the named attribute on the given object to the specified value.
    setattr(x, ‘y‘, v) is equivalent to ``x.y = v‘‘
    """
    pass

def delattr(x, y): 
    """
    Deletes the named attribute from the given object.
    delattr(x, ‘y‘) is equivalent to ``del x.y‘‘
    """
    pass

class PoloBlog:
    sum = 0

    def __init__(self, name):
        self.name = name

    def test(self):
        print("====姓名==== ", self.name)

blog = PoloBlog("小菠萝")

# hasattr
print(hasattr(blog, "name"))        # 实例对象-实例属性
print(hasattr(blog, "sum"))         # 实例对象-类属性
print(hasattr(PoloBlog, "sum"))     # 类对象-类属性
print(hasattr(PoloBlog, "name"))    # 类对象-实例属性


# 输出结果
True
True
True
False

# getattr
print(getattr(blog, "name"))  # 实例对象-实例属性
print(getattr(blog, "sum"))  # 实例对象-类属性
print(getattr(PoloBlog, "sum"))  # 类对象-类属性
print(getattr(PoloBlog, "name", "默认值"))  # 类对象-实例属性


# 输出结果
小菠萝
0
0
默认值

# 设置一个新的实例属性
setattr(blog, "age", 24)

# 设置一个新的实例方法
setattr(blog, "printNameAge", lambda self: f"姓名：{self.name} 年龄：{self.age}")

print(blog.__dict__)
print(blog.printNameAge(blog))


# 输出结果
{‘name‘: ‘小菠萝‘, ‘age‘: 24, ‘printNameAge‘: <function <lambda> at 0x10391a1f0>}
姓名：小菠萝 年龄：24

# delattr
delattr(blog, "age")
delattr(blog, "printNameAge")
print(blog.__dict__)


# 输出结果
{‘name‘: ‘小菠萝‘}

sums = 0


def test1():
    print("test")


class A():
    pass



this_module = sys.modules[__name__]
print(__name__)
print(this_module)

print(hasattr(this_module, "sums"))  # 变量
print(hasattr(this_module, "test1"))  # 方法
print(hasattr(this_module, "A"))  # 类


# 输出结果
__main__
<module ‘__main__‘ from ‘/Users/polo/Documents/pylearn/第四章：面向对象/22_反射.py‘>

True
True
True

True
反射22222
小菠萝 

class Web:
    def login(self):
        print(‘欢迎来到登录页面‘)

    def register(self):
        print(‘欢迎来到注册页面‘)

    def save(self):
        print(‘欢迎来到存储页面‘)


while True:
    obj = Web()
    choose = input(">>>").strip()
    if choose == ‘login‘:
        obj.login()
    elif choose == ‘register‘:
        obj.register()
    elif choose == ‘save‘:
        obj.save()

class Web:
    def login(self):
        print(‘欢迎来到登录页面‘)

    def register(self):
        print(‘欢迎来到注册页面‘)

    def save(self):
        print(‘欢迎来到存储页面‘)


while True:
    obj = Web()
    choose = input(">>>").strip()
    # 判断对象是否有对应的方法
    if hasattr(obj, choose):
        # 获取对应的方法
        f = getattr(obj, choose)
        # 执行方法
        f()

class BaseRequest:
    req = requests.Session()

    def get(self, url):
        resp = self.req.get(url)
        print("==get==")
        return resp

    def post(self, url):
        resp = self.req.post(url)
        print("==post==")
        return resp

    def put(self, url):
        resp = self.req.put(url)
        print("==put==")
        return resp

    # 不使用反射的方法
    def main(self, method, url):
        if method == "get":
            self.get(url)
        elif method == "post":
            self.post(url)
        elif method == "put":
            self.put(url)

    # 使用反射的方法
    def main_attr(self, method, url):
        if hasattr(self, method):
            func = getattr(self, method)
            func(url)

request = BaseRequest()
# 不使用反射
request.main("get", "http://www.baidu.com")
request.main("post", "http://www.baidu.com")
request.main("put", "http://www.baidu.com")

# 使用反射
request.main_attr("get", "http://www.baidu.com")
request.main_attr("post", "http://www.baidu.com")
request.main_attr("put", "http://www.baidu.com")


# 输出结果
==get==
==post==
==put==

==get==
==post==
==put==